150 



BASIDIOMTCETES. 



germinate should they fall on the green portions of other Grasses : 

 they then emit 2-4 germ-tubes through the equatorially-placed 

 germ-pores. The germ-tubes enter a leaf through a stoma, a 

 new mycelium is then developed, and in about eight days a fresh 

 production of uredospores takes place, which germinate as before. 

 The uredospore-mycelium very soon produces, in addition, the 

 brown teleutospores, which give a brown colour to the rust-coloured 

 spots, the familiar uredospores on the cereals being quite sup- 

 pressed towards the close of the summer (Fig. 146 C, D). The 

 " Rust of Wheat " hibernates on some wild Grasses in the uredo- 

 s pore- form. 



FIG. 147. JEcidlum lerberidis. A Portion of lower surface of leaf of Barberry, with 

 cluster-cups (acidisi). B A small portion of leaf, with spermogonia, from above. C Trans- 

 verse section of leaf on the upper side, in the palisade parenchyma are three epermogonia 

 (a b); on the lower side an unripe acidium (c d) and two ripe secidia (d, e, /); / chain of 

 secidiospores. D Hyphse, forming conidia. 



GENERA. Pitccinia (Fig. 146, 147) has bicellular teleutospores, each having 

 a germ-pore, and the aecidia when present have an indented peridium ; some 

 species, as exceptions, have 1-3-celled teleutospores. Many species are 

 HETEROZCIODS, for example, P. graminis, described above ; P. ntbiyo, which also 

 infests various Grasses, but whose tecidia appear on Ancliusa ; the masses of 



